<!DOCTYPE html>
<html>

<head>
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css">
    <script src="https://code.jquery.com/jquery-3.2.1.slim.min.js"></script>
    <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.bundle.min.js"></script> </head>

<body>
    <div class="alert alert-primary" role="alert"> 
        This is a primary alert—check it out! </div>
    <div class="alert alert-secondary"
        role="alert"> This is a secondary alert—check it out! </div>
    <div class="alert alert-success"
        role="alert"> This is a success alert—check it out! </div>
    <div class="alert alert-danger"
        role="alert"> This is a danger alert—check it out! </div>
    <div class="alert alert-warning"
        role="alert"> This is a warning alert—check it out! </div>
    <div class="alert alert-info"
        role="alert"> This is a info alert—check it out! </div>
    <div class="alert alert-light"
        role="alert"> This is a light alert—check it out! </div>
    <div class="alert alert-dark"
        role="alert"> This is a dark alert—check it out! </div>
</body>

</html>